Specialists need details of ortho-k contact lens scarring cases to advise on safe use
Recent reports from different eye institutions gave contrasting impressions of the safety of ortho-k lenses ("Bedtime lenses linked to eye infection in children", May 14).
Polytechnic University has no cases of eye damage, whereas Chinese University and the Hong Kong Eye Hospital together have 41 patients (reported between 2001 and 2010), averaging four patients per year. There may be cases from other hospitals and private ophthalmologists.
My experience, as an optometrist specialising in contact lenses, of fitting hundreds of ortho-k patients in the past 15 years is of zero cases of ulcerative keratitis.
Simple logic tells us that if the normal, proper use of ortho-k lenses caused ulcerative keratitis, then the number of reported cases must be far higher than four cases a year, given that there are thousands of users in Hong Kong. So the eye damage cases may be due to improper care and use of lenses.
Ulcerative keratitis in contact lens wearers does not occur for no reason. Daily proper cleaning of lenses after wearing is very important, especially the concave surface (the lens surface that touches the cornea). A protein film will build up on the surface of the lens if not properly cleaned. This layer rubs against the cornea, causing irritation and abrasion.
If the irritation is ignored and the person continues wearing the lenses, then the more serious ulceration may occur. Ortho-k lens users must: